GB2071216A - Beverage dispensing by direct gas pressure - Google Patents

Abstract

A beverage dispensing system has a container 2 from which beverage 1 is to be dispensed by a gaseous mixture of air and carbon dioxide from passage 3 in headspace 4. Pressurised mixed gases for dispensing are derived from a compressor 12. Carbon dioxide 9 is capable of communication with the compressor by way of a diaphragm valve 16 which normally closes communication between the carbon dioxide source 9 and the compressor. Diaphragm 21 of valve 16 is responsive to reductions in pressure derived from operation of the compressor 12 so that the valve 16 opens communication between the carbon dioxide source 9 and the compressor when mixed gases are demanded. <IMAGE>

Description

SPECIFICATION A beverage dispensing system This invention relates to a beverage dispensing system.

More particularly, the invention concerns the dispensing of a beverage from a bulk container such as a cask or a keg by the admission of gas under pressure to the container.

According to the present invention there is provided a beverage dispensing system comprising a container from which the beverage is to be dispensed by pressure of a gaseous mixture of carbon dioxide and a second gas comprising nitrogen; a source of said second gas which is to communicate under pressure and on demand with the container; a source of carbon dioxide under pressure which is capable of communication with the container by way of valve means and wherein said valve means is responsive to gaseous pressure in the system whereby upon the gaseous mixture being demanded for dispensing, pressure means by which the second gas under pressure is supplied on demand causes a reduction in pressure on the valve means and thereby actuation of the valve means to open communication between the source of carbon dioxide and the container and upon the demand for the gaseous mixture ceasing the valve means closes communication between the source of carbon dioxide and the container.

The invention was primarily developed for the dispensing of fermented liquor such as beer (by which is included lager, ale or stout) which will usually but not invariably, be carbonated. By the system of the present invention the second gas can consist of nitrogen which is derived, for example, from a pressurised cylinder and supplied to the system by way of an appropriate reducing valve for the dispensing of, for example beer, from a cask. A mixture of carbon dioxide gas and a second gas which consts of, or is preferably primarily of, nitrogen is used to alleviate excessive carbonation of the beer (which can result by the use of carbon dioxide on its own at sufficient pressure to dispense the beer from the container).

Consequently the nitrogen gas content can be regarded as being provided to dilute the carbon dioxide content although there are of course many well known advantages for dispensing beer under pressure with mixed gases of nitrogen and carbon dioxide for example, to achieve a stable and aesthetically pleasing (creamy) head on the beer when dispensed. The supply of a gaseous nitrogen and carbon dioxide mixture is relatively expensive as compared with the supply of carbon dioxide on its own. It is preferred therefore that the second gas is air and the system of the present invention envisages the use of the nitrogen content of air as a diluent for the carbon dioxide to avoid excessive carbonation in the beverage. A source of pressurised air is obtainable relatively inexpensively, for example from a compressor.

To alleviate the aforementioned excessive carbonation of the beverage in the container it is a feature of the invention that the source of carbon dioxide is maintained out of communication with the beverage until a flow of pressurised mixed gases is required; with this in mind the valve means is provided which normally closes communication between the source of carbon dioxide and the container but which valve means is responsive to a demand for the mixed gases for dispensing.This response may be caused by a reduction in pressure on the valve means effected by the pressurised flow of, or by the direct or indirect effect of pressurising, the air or other second gas for dispensing which results in the valve means opening communication between the source of carbon dioxide and the container so that dispensing is effected by the pressurised mixture of carbon dioxide and the air (or other second gas comprising nitrogen) which is admitted to the container. When the demand for the mixed gases ceases there is an appropriate variation in pressure on the valve means which results in such means closing communication between the source of carbon dioxide and the container.

More particularly, the invention provides a beverage dispensing system comprising a bulk beer container from which the beverage is to be dispensed; a source of air under pressure from which pressurised air is available for admission to the container on demand for dispensing the beverage; a source of carbon dioxide under pressure from which pressurised carbon dioxide is capable of communication by way of valve means with the container for dispensing of the beverage as a gaseous mixture with said air under pressure; said valve means being responsive to a reduction in pressure in the system resulting from air pressurisation being effected for dispensing so that said valve means is actuated to open communication between the carbon dioxide source and the container by pressurised air being demanded and is actuated to close communication between the carbon dioxide source and the container by pressure variation which results in the system when the demand for air pressurisation ceases.

The valve means is desiraóly biased to a normally closed condition where the source of carbon dioxide is closed to communication with the container so that when the valve means is actuated in response to the demand for mixed gases under pressure for dispensing it is displaced against its biasing to open communication between the carbon dioxide source and the container. Preferably the valve means is pressure biased to its closed condition by the pressure of carbon dioxide from the carbon dioxide source which is arranged to be in constant communication with the valve means. The source of carbon dioxide will usually be a storage bottle from which the carbon dioxide supply is derived, directly or by way of a ring main, through a reducing valve.

In a prior proposal of a beverage dispensing system which is the subject of our co-pending Application No. 78 33495, actuation of valve means to effect supply of carbon dioxide to a cask as a mixture with air results from the development of pressure of the air in the system by a compressor. This development of air pressure by the compressor serves to cause an increase in pressure on the valve means whereby the valve means is actuated in response to a pressure differential which is effected on it (partly by the compressed air) to permit the flow of carbon dioxide under pressure. The carbon dioxide flow is then mixed, downstream of the valve means and of the air compressor, with the compressed air for dispensing.To achieve appropriate pressure differential on the valve means, gas flow restrictors are provided in the air line downstream of the compressor and of the valve means and also in the carbon dioxide line downstream of the valve means - in each case the restrictors are located upstream of the junction between the air and carbon dioxide lines where the gases are mixed.

With this arrangement of our prior proposal it is possible that if the system is operated in a humid atmosphere (and where there are no facilities or agents for drying the air) water drop-out will be experienced causing condensation downstream of the air compressor and upstream of the restrictor in the air line and this water drop-out may create a blockage in the air line restrictor to disrupt flow.

To alleviate this latter possibility and in accordance with one preferred embodiment of the present invention, pressure means in the form of a compressor can be located in the system downstream of the valve means to communicate with, and be common to both, carbon dioxide which emanates from the valve means and to the air (or other second gas) which gases are mixed prior to, or on entering, the compressor for pressurising and subsequent supply to the container for dispensing. With this latter arrangement operation of the compressor to induce air serves to provide a decrease in pressure on the valve means causing the latter to be actuated to open communication between the source of carbon dioxide and the compressor and thereby the container.Actuation of the valve means is effected by the pressure differential to which it is subjected by the decrease in pressure resulting from operation of the compressor. To achieve such a differential and also to control the proportions in which the gases are mixed, gas flow restrictors will usually be provided in the air line upstream of the compressor and also in the carbon dioxide line upstream of the compressor but downstream of the valve means. However, since the mixed gases are compressed (particularly the air) downstream of the restrictors any water drop-out which may occur as a result of such compression will be without effect on the efficiency of the restrictors.

In a further preferred embodiment of the present invention, actuation of the valve means to effect supply of carbon dioxide to the container results from the development of pressure of the second gas on demand by first pressure means which first pressure means is coupled to second pressure means, the latter being actuated in response to actuation of the first pressure means and actuation of the second pressure means causing the valve means to be actuated. Actuation of the second pressure means causes a reduction in pressure on the valve means and thereby a pressure differential to be applied to the valve means which results in the valve means responding to open communication between the source of carbon dioxide and the container.

Preferably the first pressure means is a first compressor to which air (or other second gas) is supplied by way of a first passage and the second pressure means is a second compressor which is located in a second passage downstream of the valve means from which it receives carbon dioxide. The first and second compressors are coupled for simultaneous operation to pressurise the air and carbon dioxide respectively which pressurised gases emerge from their respective compressors to be mixed prior to or on entering the container for dispensing. With this arrangement the first and second compressors may be separate but coupled together electrically or otherwise for simultaneous operation when there is demand for mixed gases or they may have a common drive motor and be, for example, in the form of a double ended compressor.It will be apparent that on operation of the second compressor to induce carbon dioxide the reduction in pressure on the valve means upstream thereof serves to apply a pressure differential to the valve means causing the latter to be actuated. Since the air (or other second gas) and the carbon dioxide are independently pressurised for subsequent admixture by this further form of the invention and since the valve means is responsive to a pressure differential effected by operation of the compressor in the carbon dioxide line, gas flow restrictors can be omitted from the system so there is no possibility of the efficiency of such restrictors being impaired by water drop-out; furthermore a high flow rate of mixed gases can be achieved.

The valve means preferably has a displaceable valve member which is responsive to displacement of a diaphragm to open and close communication between the source of carbon dioxide and the container. This diaphragm is intended to be displaceable in response to the pressure differential which is developed across it in response to reductions in gas pressure in the system which may be achieved as previously described. In the above described systems in accordance with the present invention the displaceable diaphragm of the valve means may partly define a chamber the pressure within which is decreased in response to development of pressure of the second gas by the aforementioned first pressure means or in response to actuation of the second pressure means. This pressure decrease causes a pressure differential to develop across the diaphragm and displacement of the valve member to open communication between the source of carbon dioxide and the container. For so long as a sufficient pressure differential exists across the diaphragm, for example the differential may be achieved by subjecting one side of the diaphragm to atmospheric pressure and the other side of the diaphragm to carbon dioxide under reduced pressure, a balanced or modulating position of the valve member can be attained whereby it is displaced from its normally closed condition to maintain the carbon dioxide supply to the container together with the air (or other second gas) supply.Upon a cease in the demand for mixed gases the pressure differential across the diaphragm decreases until the valve member is displaced to close communication between the carbon dioxide supply and the container. To ensure a rapid return of the valve member to its normally closed condition it is preferred that this member is biased into that condition by carbon dioxide under pressure derived from the source with which the valve member may be in constant communication. To provide such gas pressure biasing the valve member is conveniently in the form of a spool which is axially displaceable in a housing of the valve means and is coupled to the diaphragm for such displacement in response to displacement of the diaphragm.The spool has axially opposed faces with different effective areas of which the face with the larger effective area is in constant communication with the source of carbon dioxide whereby gas pressure reacting on said opposed faces provides a biasing force on the valve member to urge it to its normally closed condition when a demand for the mixed gases ceases.

When the second gas (usually air) and also the carbon dioxide as necessary, is pressurised by one or more compressors in the system, such compressors can be arranged to have a delivery commensurate with the rate at which beverage is drawn from the container and can be actuated in response to operation of a tap or other valve which is open to draw beverage from the container.Preferably however operation of the compressor (or admission into the system otherwise of a second gas such as nitrogen from a pressurised bottle) is controlled by a pressure switch which is responsive to the pressure of mixed gases in the head of the container so that when this pressure falls below a predetermined value (as will usually occur upon dispensing of the beverage) the compressor or compressors are actuated (or admission otherwise of the second gas is effected) automatically and cut out upon the predetermined mixed gas pressure being attained.

Where gas flow restrictors are incorporated in the system it will be apparent that such restrictors may be adjustable.

Embodiments of beverage dispensing systems constructed in accordance with the present invention will now be described, by way of example only, with reference to the accompanying illustrative drawings, in which: Figure 1 is a diagrammatic illustration of a first system in which pressurisation of the gases is effected subsequently to them being mixed and in common pressurising means; Figure 2 illustrates, in section, valve means for controlling carbon dioxide flow in the system of Figure 1; Figure 3 illustrates in part section a valve member of the valve means of Figure 2; Figure 4 is a diagrammatic illustration of a second system in which independent pressurisation of the gases is effected prior to them being mixed, and Figure 5 illustrates, in section, valve means for controlling carbon dioxide flow in the system of Figure 4.

Each of the systems as shown in the Figures is intended for dispensing beer or stout 1 from a cask 2 whereby gas under pressure is supplied through passage 3 into the headspace 4 of the cask to dispense the beverage (by way of a riser tube 5 and a control tap 6) through a nozzle 7. The gas for pressurising the headspace 4 is formed by a mixture of gaseous carbon dioxide and air of which the air is drawn into the system through a bacterial filter 8 and the carbon dioxide supply is from a pressurised bottle 9 through a pressure regulator 10 and a carbon dioxide passage line 11.

In the embodiment of Figures 1 to 3 a compressor 12 is provided which draws in mixed gases for compression by way of a passage 13.

One of these mixed gases is air which passes by way of filter 8 and a restrictor 14 in passage 1 5 which communicates with the passage 1 3. The other gas of the mixture is carbon dioxide supplied by way of the line 11, valve means 1 6 and a passage 1 7 which communicates by way of a restrictor 18 with the passage 1 3. If required, a filter 1 9 for the carbon dioxide can be incorporated in the passage 1 7. Pressurised mixed gases emanating from the compressor 12 communicate through the line 3 with the headspace 4 of the cask 2.

The valve means 1 6 (see Figure 2) comprises a housing 20 within which is mounted a diaphragm 21. Formed on one side of the diaphragm and within the housing 20 is a chamber 22 which is open to atmospheric pressure by way of a passage 23. A second chamber 24 is formed within the housing 20 on the opposite side of the diaphragm 21. Connected to the diaphragm 21 through the chamber 24 by a spool rod 25 is a spool 26 which is axially displaceable (in response to displacement of the diaphragm) within an aperture 27 in a partition wall 28 of the housing 20. The partition wall 28 partly defines a sub-chamber 29 on the side thereof remote from the chamber 24 and this sub-chamber 29 is in constant communication with the carbon dioxide supply line 11.The spool 26 of the valve means 16 is capable, by its axial displacement, of opening and closing communication by way of the aperture 27 between the sub-chamber 29 and the chamber 24. As shown in Figure 3 the spool 26 is of tapered configuration with the larger diameter head part projecting into the sub-chamber 29 and this head part, when the spool is in its closed condition (as shown by the full lines in Figure 3) abuts an annular seal 30 seated in a rebate in the partition wall 28. The spool 26 tapers from its head part to the spool rod 35 and this tapered configuration provides a differential pressure operated type valve where the spool, in effect, has axially opposed faces 31 and 32 with different effective areas of which the face 32 on the head part and which opens into the sub-chamber 29 is of larger effective area than the face 31 which opens to the chamber 24.A compression spring 33 is provided in the chamber 22 to react between the housing 20 and the diaphragm 21 to bias the diaphragm for displacement in a direction which displaces the spool 26 to open the aperture 27.

The chamber 20 is in constant communication with the passage 17 and thereby through the restrictor 1 8 with the compressor 12.

Located in the line 3 is a pressure switch 34 which controls actuation of the compressor 12so that when the pressure of mixed gases in the headspace 4 falls below a predetermined pressure as required for dispensing purposes the switch 34 automatically starts operation of the compressor 12 and also switches off the compressor when the required pressure of mixed gases in the headspace is attained.

When the compressor 12 is actuated by the pressure switch 34 air is drawn into the compresso; through passage 15, restrictor 14 and passage 13. In addition the operation of the compressor 12 causes a reduction of pressure in the chamber 24 of valve 16 through passage 13, restrictor 18 and passage 1 7. Such a reduction in pressure in the chamber 24 causes the diaphragm 21, assisted by the spring 33, to be stressed and displaced downwardly in Figure 2 to open the aperture 27 from the spool 26 (as shown by the broken lines in Figure 3) and thereby open communication between carbon dioxide in the line 11 to the chamber 24 and consequently with the compressor 12. Air and carbon dioxide in mixture are therefore supplied to the compressor 12 for pressurisation and subsequent supply by way of passage 3 to the headspace for dispensing purposes.When the pressure of the mixed gases in the headspace 4 attains that required for dispensing the compressor 12 is shut off by the pressure switch 34. As a consequence the pressure in the line 1 7 and thereby in the chamber 18 approaches atmospheric pressure and the pressure of carbon dioxide in the sub-chamber 29 reacting on face 32 of the head part of the spool 26 effects in final rapid displacement of the spool to close the aperture 27 by gas pressure differential; as will be appreciated this displacement of the spool to close the aperture 27 will be assisted, and probably initiated, by the tendency of the diaphragm to revert to its normal unstressed, condition.

The proportions in which the air and carbon dioxide are supplied for mixture along the passage 13 and in the compressor 12 can be controlled in part by appropriate selection of the restrictors 14 and 1 8. Furthermore, the opening and closing of the aperture 27 by the spool 26 can be controlled by appropriate selection of the spring 33.

It will be apparent from Figure 1 that compression of the air is effected downstream of the restrictor 14 (and also of restrictor 18).

Consequently if the system is operated in a humid atmosphere (and in the absence of drying agents or other facilities for drying the air) any water drop-out or condensation which may result from the air compression will be without effect on the restrictor 14 (or on the restrictor 18). Since the compressor 12 also serves to pressurise the carbon dioxide as a mixture with the air it is preferred that the carbon dioxide is supplied to the valve means 16, at a pressure greater than atmospheric which is subsequently reduced in passing through the valve 16, to approximately atmospheric or sub-atmospheric pressure in the line 17 (when the compressor is operating).In a typical system the regulator valve 10 of the carbon dioxide supply is arranged for the carbon dioxide in line 11 to be at approximately 34 pounds per square inch (absolute) and the restrictors 14 and 1 8 are arranged to supply mixed gases in the proportion 40% carbon dioxide, 60% air.

A pressure gauge 35 is provided in the passage 3 for convenience of inspecting the pressure of mixed gases which is available for dispensing. A pressure switch 36 can be provided as an optional feature in the carbon dioxide passage line 11 which is arranged to stop the compressor 12 in the event that the pressure of carbon dioxide in the line 11 falls below a predetermined minimum, for example should the carbon dioxide cylinder 9 empty.

The system in the embodiment of Figures 4 and 5 (in which the cask and carbon dioxide source have been omitted for convenience) is similar in many respect to that shown in the first embodiment with two main exceptions in that two compressors 37 and 38 are provided and the restrictors have been omitted. The compressors 37 and 38 are coupled together for simultaneous operation under control of the pressure switch 34 and conveniently these compressors are driven by a common motor (in the manner of a double ended compressor); for practical purposes the characteristics and performances of the compressors may be identical. As shown in Figure 4 the compressor 37 communicates directly through passage 1 5 and filter 8 with air while compressor 38 is intended to communicate with the carbon dioxide line 11 by way of filter 1 9, passage 17 and valve means 16'. The valve means 1 6' operates in response to a pressure reduction effected by actuation of the compressor 38 in a similar manner to the valve means 1 6 of the first embodiment to open communication between carbon dioxide in the line 11 and the compressor 38.

On operation of the coupled compressors 37 and 38 by the pressure switch 34 in demand for pressurised mixed gases for dispensing, air is drawn into the compressor 37 by way of filter 8 and passage 1 5 whilst carbon dioxide is simultaneously drawn into the compressor 38 through valve means 16', passage 1 7 and filter 10. The pressurised air emerging from the compressor 37 communicates by way of a passage 39 with the line 3 while the pressurised carbon dioxide from the compressor 38 also communicates with the line 3 through a passage 40 and consequently it is not until after compression of the respective gases and until in the line 3 for passage to the headspace 4 that the gases are mixed.

As previously mentioned the valve means 16' (see Figure 5 is similar in all major respects to the valve means 1 6 as shown in Figure 2. However the valve 1 6' incorporates means for varying the biasing effect of spring 33 and as shown in Figure 5 this means comprises a screw 41 in the housing 20 and against which screw the spring 33 reacts so that by adjustment of the screw the force exerted by the spring on the diaphragm 21 is adjustable. A lock nut 42 is provided on the screw 41 to secure it in an appropriate adjusted position.

The omission of restrictors from the embodiment of Figures 4 and 6 again alieviates the likelihood of the required supply of mixed gases being disrupted by water drop-out due to the compression of air; furthermore it permits higher flow rates of mixed gases than that which can be achieved when using restrictors in the respective air and carbon dioxide lines. Since the restrictors have been omitted from the embodiment of Figure 4 the relative proportions in which the gases are mixed can be controlled wholly by the valve means 16' by appropriate adjustment of the screw 41 and thereby compression in the spring 33 to give the required characteristics for opening of the spool 26 to admit carbon dioxide into the system for mixing when the compressors 37 and 38 are actuated; for example, as the compressive force in spring 33 is increased by adjustment of the screw 41 then the greater is the proportion of carbon dioxide which will be admitted for pressurisation and subsequent admixture with the air.

Usually non-return valves will be provided in the air and carbon dioxide lines to the compressor or compressors in Figures 1 and 4 but these have been omitted from the drawings for convenience.

Claims (17)

1. A beverage dispensing system comprising a container from which the beverage is to be dispensed by pressure of a gaseous mixture of carbon dioxide and a second gas comprising nitrogen; a source of said second gas which is to communicate under pressure and on demand with the container; a source of carbon dioxide under pressure which is capable of communication with the container by way of valve means and wherein said valve means is reponsive to gaseous pressure in the system whereby upon the gaseous mixture being demanded for dispensing, pressure means by which the second gas under pressure is supplied on demand causes a reduction in pressure on the valve means and thereby actuation of the valve means to open communication between the source of carbon dioxide and the container and upon the demand for the gaseous mixture ceasing the valve means closes communication between the source of carbon dioxide and the container.

2. A system as claimed in claim 1 in which the second gas is air.

3. A system as claimed in either claim 1 or claim 2 in which the valve means is biased to a normally closed condition where the source of carbon dioxide is closed to communication with the container so that when said valve means is actuated in response to the demand for the gaseous mixture the valve means is displaced against its biasing to open communication between the carbon dioxide source and the container.

4. A system as claimed in claim 3 in which the carbon dioxide source is in constant communication with the valve means and said valve means is pressure biased to its closed condition by pressure of carbon dioxide from said carbon dioxide source.

5. A system as claimed in any one of the preceding claims in which the development of pressure of said second gas in the system by said pressure means causes the decrease in pressure on the valve means which actuates the valve means to open communication between the source of carbon dioxide and the container.

6. A system as claimed in claim 5 in which the pressure means is located in the system downstream of the valve means and wherein carbon dioxide emanating from the valve means and said second gas are mixed to provide said gaseous mixture for pressurising by said pressure means which is common to both said gases.

7. A system as claimed in claim 6 in which said second gas communicates with the pressure means by way of a first gas flow restrictor and the carbon dioxide communicates with the pressure means by way of a second gas flow restrictor located downstream of the valve.

8. A system as claimed in any one of the preceding claims in which the pressure means comprises a compressor.

9. A system as claimed in any one of claims 1 to 4 in which the development of pressure of said second gas in the system on demand is by first said pressure means which first pressure means is coupled to second pressure means, said second pressure means being actuated in response to actuation of the first pressure means and actuation of the second pressure means causes a decrease in pressure on the valve means to open communication between the source of carbon dioxide and the container.

10. A system as claimed in claim 9 in which the first pressure means comprises a first compressor and the second pressure means comprises a second compressor coupled two the first compressor for simultaneous operation therewith, and wherein the first compressor is located in first passage means through which the second gas is supplied and the second compressor is located in second passage means downstream of the valve means from which it receives carbon dioxide, the compressed second gas and carbon dioxide gas emanating from the respective compressors being mixed for supply on demand to the container for dispensing.

11. A system as claimed in any one of the preceding claims in which said valve means comprises a displaceable valve member which is responsive to displacement of a diaphragm to open and close communication between the source of carbon dioxide and the container and wherein said diaphragm is displaceable in response to a pressure differential which is developed across it in response to variations in gas pressure in the system.

12. A system as claimed in claim 11 wherein the displaceable diaphragm partly defines a chamber gaseous pressure within which said pressure reduction is effected to cause a pressure differential to develop across the diaphragm and displacement of the valve member to open communication between the source of carbon dioxide and the container.

13. A system as claimed in claim 12 wherein the side of the diaphragm remote from said chamber is open to atmospheric pressure.

14. A system as claimed in any one of claims 11 to 13 in which the valve member is in constant communication with the carbon dioxide source and is biased to its closed condition by pressure of carbon dioxide from said source.

1 5. A system as claimed in claim 14 in which the valve member comprises a spool which is axially displaceable in a housing of the valve means and is coupled to the diaphragm for such displacement in response to displacement of the diaphragm; said spool having axially opposed faces with different effective areas of which the face with the larger effective area is in constant communication with the source of carbon dioxide whereby gas pressure reacting on said opposed faces provides a biasing force on the valve member to urge it to its normally closed condition -when a demand for the mixed gases ceases.

16. A system as claimed in any one of the preceding claims in which admission into the system of said second gas by said pressure means is controlled by pressure switch means which is responsive to mixed gas pressure in the container whereby when said mixed gas pressure falls below a predetermined value admission of said second gas and thereby carbon dioxide is effected automatically and when said mixed gas pressure attains a predetermined value said admission ceases automatically.

17. A beverage dispensing system comprising a bulk beer container from which the beverage is to be dispensed; a source of air under pressure from which pressurised air is available for admission to the container on demand for dispensing the beverage; a source of carbon dioxide under pressure from which pressurised carbon dioxide is capable of communication by way of valve means with the container for dispensing of the beverage as a gaseous mixture with said air under pressure; said valve means being responsive to a reduction in pressure in the system resulting from air pressurisation being effected for dispensing so that said valve means is actuated to open communication between the carbon dioxide source and the container by pressurised air being demanded and is actuated to close communication between the carbon dioxide source and the container by pressure variation which results in the system when the demand for air pressurisation ceases.

1 8. A beverage dispensing system substantially as herein described with reference to Figures 1 to 3 of the accompanying illustrative drawings.

1 9. A beverage dispensing system substantially as herein described with reference to Figures 4 and 5 of the accompanying illustrative drawings.